Magnetic resonance imaging (MRI) of the breast is quickly becoming an important component of breast cancer screening in the United States. The American Cancer Society revised its MRI screening guidelines in 2007 to include women with a 20 to 25 percent increased lifetime risk, including family history of breast and ovarian cancers or a history of prior treatment for Hodgkin's disease. MRI has become a tool for breast cancer screening because of its advantages over mammography and ultrasound. First, breast MRI is more sensitive than x-ray mammography and ultrasound and thus may be used to detect lesions that would otherwise remain undetected. Second, MRI has been shown to be advantageous in screening women with dense breast tissue, which is common in younger patients. Third, and likely most importantly, the dynamic contrast enhanced (DCE) component of DCEMRI provides information about vascularity of a lesion that is more difficult to obtain using x-ray mammography or ultrasound.
Triple negative (TN) breast cancer has recently gained much attention in the field of breast cancer research. TN breast cancer is a molecular subtype that lacks expression of the estrogen receptor, progesterone receptor, and the HER2 receptor. Because of its lack of receptor expression, targeted therapies are ineffective, and chemotherapy is currently the only treatment available. TN breast cancer is also particularly aggressive and accounts for 12% to 26% of all breast cancers, most often occurring in young patients and African-American patients. The research community has become interested in TN breast cancer because of its particularly aggressive clinical course and lack of targeted therapies. Studies examining the pathological phenotype have revealed a heterogeneous group of breast cancers that often present as interval cancers, presenting in the months in between annual breast cancers screenings. This clearly suggests the need for greater exploration into the detection methods and biological understanding of TN breast cancers. Studies have shown that x-ray mammography is less effective in TN breast cancer screening than DCE-MRI due to the greater sensitivity of DCE-MRI in detecting TN and basal-like breast cancer phenotypes. A similar pattern of enhancement, described as rim enhancement, was observed in both subtypes. Although, qualitative radiologic descriptors have been developed for small pilot studies in TN breast cancer cases, the inventors are unaware of any quantitative classification of the TN subtype.